|What:| GIT - Fast Distributed Version Control System (DVCS)|
|Where:| http://git-scm.com/ <
> http://www.gitscm.org/ <
> http://ozlabs.org/~paulus/gitk/|
|Description:| Git is popular version control system designed to handle very large projects with speed and efficiency; it is used mainly for various open source projects, most notably the Linux kernel.|
|| Currently at version v1.6.5.2|
|Updated:| 11/2009|
|Contact:| See web site|
It is related to Tcl/Tk because there is [gitk], a history visualization tool written in Tcl/Tk.
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Branches in git are kind of like variables in Tcl.
When one makes a commit, one creates a commit object, that "contains" the parent commit(s) and a directory tree specifying the current state of one's working directory, kind of like:
======
proc commit {} {
upvar #0 $::current_branch current
set current [list commit $::current_tree $current]
}
======
(Rather than referencing things with pointers to [Tcl_Obj]s however, things are referenced with 160-bit [sha1] hashes.)
Deleting a branch is like unsetting a variable: if that variable held the only reference to a particular value (commit), then the commit is gone too, but if anything else held another reference (e.g., it was merged into another branch, which results in a commit with more than one parent), then the commit is still there.
Of course, since all of it is stored on disk, it would be impractical to use a refcount scheme to reclaim unused memory. Instead git has a garbage collector git-gc. Until that is run, deleted commits (and whatever) can still be accessed by giving explicit hash numbers.
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[Zarutian] 16. july 2007: Can git be obtained or compiled into a multiplatform starkit?
Hard when one has only an thumbdrive/ipod to store stuff.
[Lars H], 2008-06-05: Since it's a Unixy collection of many programs that do one thing each, I suspect this would be tricky (can't [exec] something in a [vfs], can you?). Apparently there has been some work [http://git.or.cz/gitwiki/SoC2007Projects#head-f604c29a605c7c5fe1e993ef5aa74ce34f3fb84e] on turning it into a library, but that only got part of the way.
Makes me wonder, though… Could there be a semi-automatic way of turning a suite of C programs (like git, or at least the git plumbing) into a [load]able extension which exposes each program as a Tcl command? (I expect one would have to do things like turning static C variables into fields of some dynamically allocated struct, to ensure reentrancy, but C is not my forte.)
FWIW, I later noticed that git has a concept of '''builtin''' command, with something rather close to a Tcl_CmdProc for every built-in subcommand of git. Probably not too hard to wrap manually, provided the built-in commands don't try to exec each other.
[MAKR] 2009-02-01: I updated the URLs as the main site apparently changed recently.
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[RJM] 2010-10-05 added a page regarding an attempt to allow timestamp preservation of files: [git timestamps]
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A thing that seems to be special about Git is that it tracks content (e.g. procedure definitions) rather than files (as [CVS], [SVN], and [Mercurial] does).
See [http://wincent.com/a/about/wincent/weblog/archives/2007/07/a_look_back_bra.php].
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